Nanorings

March 05, 2008

What appear under an atomic force microscope to be tiny rings with little bits missing are actually nanoscopic rings made of double-stranded DNA with a little gap in the form of a short single-stranded fragment. As Michael Famulok and his team from the University of Bonn, Germany, explain in the journal Angewandte Chemie , this gap is a place to attach other molecules that have the potential to transform the rings into versatile nanocomposites for various applications.

The programmable aggregation of molecular building blocks into structures with higher order plays a key role in the construction of nanomaterials. Nucleic acids are interesting building block candidates, being easy to synthesize and exhibiting unique molecular recognition characteristics. The difficulty lies in the fact that the construction of defined two- or three-dimensional geometries requires rigid building blocks. However, DNA molecules are normally flexible structures.

"From the structural point of view, miniature rings represent the simplest form for a rigid object made of DNA," says Famulok. His team thus took on the challenge of producing DNA molecules with a smooth circular structure, free of ring deformations, twists, or knots. This was not an easy endeavor. DNA is usually found in the form of a double strand with a helical twist and can, if it is too short, close on itself to form a ring. On the other hand, if the ring gets too large, it is no longer rigid. Famulok and his team have now succeeded, by careful selection of the sequence and number of nucleotides as well as a clever synthetic route, in producing the desired rigid rings.

Even better, the researchers were able to build a "gap" into their rings--a short sequence that does not occur in normal base pairing, instead exiting as a single-stranded segment. This should make it possible to "fit" the ring with tailored functionality for special applications. All that needs to be done is to produce a short single strand of DNA complementary to the single-stranded part of the ring and to attach it to a molecule with the desired properties. This single strand then fits perfectly into the gap. This allows the ring to be equipped as desired, depending on the requirements of the application in question. For example, it can be given "anchors" that precisely bind the rings to other components.

"Our new, uncomplicated method for the production of rigid DNA nanorings with variable, tailor-made functionality opens new pathways for the construction of DNA objects with higher levels of organization," Famulok is convinced.
-end-
Author: Michael Famulok, Universität Bonn (Germany), http://www.chembiol.uni-bonn.de/index-e.html
Title: DNA Minicircles with Gaps for Versatile Functionalization
Angewandte Chemie International Edition, doi: 10.1002/anie.200704004

Wiley

Related DNA Articles from Brightsurf:

A new twist on DNA origami
A team* of scientists from ASU and Shanghai Jiao Tong University (SJTU) led by Hao Yan, ASU's Milton Glick Professor in the School of Molecular Sciences, and director of the ASU Biodesign Institute's Center for Molecular Design and Biomimetics, has just announced the creation of a new type of meta-DNA structures that will open up the fields of optoelectronics (including information storage and encryption) as well as synthetic biology.

Solving a DNA mystery
''A watched pot never boils,'' as the saying goes, but that was not the case for UC Santa Barbara researchers watching a ''pot'' of liquids formed from DNA.

Junk DNA might be really, really useful for biocomputing
When you don't understand how things work, it's not unusual to think of them as just plain old junk.

Designing DNA from scratch: Engineering the functions of micrometer-sized DNA droplets
Scientists at Tokyo Institute of Technology (Tokyo Tech) have constructed ''DNA droplets'' comprising designed DNA nanostructures.

Does DNA in the water tell us how many fish are there?
Researchers have developed a new non-invasive method to count individual fish by measuring the concentration of environmental DNA in the water, which could be applied for quantitative monitoring of aquatic ecosystems.

Zigzag DNA
How the cell organizes DNA into tightly packed chromosomes. Nature publication by Delft University of Technology and EMBL Heidelberg.

Scientists now know what DNA's chaperone looks like
Researchers have discovered the structure of the FACT protein -- a mysterious protein central to the functioning of DNA.

DNA is like everything else: it's not what you have, but how you use it
A new paradigm for reading out genetic information in DNA is described by Dr.

A new spin on DNA
For decades, researchers have chased ways to study biological machines.

From face to DNA: New method aims to improve match between DNA sample and face database
Predicting what someone's face looks like based on a DNA sample remains a hard nut to crack for science.

Read More: DNA News and DNA Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.